doc/plugins/contrib/unixauth.mdwn

   1 [[!template id=plugin name=unixauth core=0 author="[[schmonz]]"]]
   2 [[!tag type/auth]]
   3
   4 This plugin authenticates users against the Unix user database. It presents a similar UI to [[plugins/passwordauth]], but simpler, as there's no need to be able to register or change one's password.
   5
   6 To authenticate, either [checkpassword](http://cr.yp.to/checkpwd.html) or [pwauth](http://www.unixpapa.com/pwauth/) must be installed and configured. `checkpassword` is strongly preferred. If your web server runs as an unprivileged user -- as it darn well should! -- then `checkpassword` needs to be setuid root. (Or your ikiwiki CGI wrapper, I guess, but don't do that.) Other checkpassword implementations are available, notably [checkpassword-pam](http://checkpasswd-pam.sourceforge.net/).
   7
   8 Config variables that affect the behavior of `unixauth`:
   9
  10 * `unixauth_type`: defaults to unset, can be "checkpassword" or "pwauth"
  11 * `unixauth_command`: defaults to unset, should contain the full path and any arguments
  12 * `unixauth_requiressl`: defaults to 1, can be 0
  13 * `sslcookie`: needs to be 1 if `unixauth_requiressl` is 1 (perhaps this should be done automatically?)
  14
  15 __Security__: [As with passwordauth](/security/#index14h2), be wary of sending usernames and passwords in cleartext. Unlike passwordauth, sniffing `unixauth` credentials can get an attacker much further than mere wiki access. Therefore, this plugin defaults to not even _displaying_ the login form fields unless we're running under SSL. Nobody should be able to do anything remotely dumb until the admin has done at least a little thinking. After that, dumb things are always possible. ;-)
  16
  17 `unixauth` needs the `HTTPS` environment variable, available in ikiwiki 2.67 or later (fixed in #[502047](http://bugs.debian.org/502047)), without which it fails closed.
  18
  19 The plugin has not been tested with newer versions of ikiwiki. [[schmonz]] hopes to have time to polish this plugin soon.
  20
  21 [[!toggle id="code" text="unixauth.pm"]]
  22
  23 [[!toggleable id="code" text="""
  24
  25     #!/usr/bin/perl
  26     # Ikiwiki unixauth authentication.
  27     package IkiWiki::Plugin::unixauth;
  28
  29     use warnings;
  30     use strict;
  31     use IkiWiki 2.00;
  32
  33     sub import {
  34         hook(type => "getsetup", id => "unixauth", call => \&getsetup);
  35             hook(type => "formbuilder_setup", id => "unixauth",
  36                 call => \&formbuilder_setup);
  37             hook(type => "formbuilder", id => "unixauth",
  38                 call => \&formbuilder);
  39         hook(type => "sessioncgi", id => "unixauth", call => \&sessioncgi);
  40     }
  41
  42     sub getsetup () {
  43         return
  44         unixauth_type => {
  45                 type => "string",
  46                 example => "checkpassword",
  47                 description => "type of authenticator; can be 'checkpassword' or 'pwauth'",
  48                 safe => 0,
  49                 rebuild => 1,
  50         },
  51         unixauth_command => {
  52                 type => "string",
  53                 example => "/path/to/checkpassword",
  54                 description => "full path and any arguments",
  55                 safe => 0,
  56                 rebuild => 1,
  57         },
  58         unixauth_requiressl => {
  59                 type => "boolean",
  60                 example => "1",
  61                 description => "require SSL? strongly recommended",
  62                 safe => 0,
  63                 rebuild => 1,
  64         },
  65         plugin => {
  66                 description => "Unix user authentication",
  67                 safe => 0,
  68                 rebuild => 1,
  69         },
  70     }
  71
  72     # Checks if a string matches a user's password, and returns true or false.
  73     sub checkpassword ($$;$) {
  74         my $user=shift;
  75         my $password=shift;
  76         my $field=shift || "password";
  77
  78         # It's very important that the user not be allowed to log in with
  79         # an empty password!
  80         if (! length $password) {
  81                 return 0;
  82         }
  83
  84         my $ret=0;
  85         if (! exists $config{unixauth_type}) {
  86                 # admin needs to carefully think over his configuration
  87                 return 0;
  88         }
  89         elsif ($config{unixauth_type} eq "checkpassword") {
  90                 open UNIXAUTH, "|$config{unixauth_command} true 3<&0" or die("Could not run $config{unixauth_type}");
  91                 print UNIXAUTH "$user\0$password\0Y123456\0";
  92                 close UNIXAUTH;
  93                 $ret=!($?>>8);
  94         }
  95         elsif ($config{unixauth_type} eq "pwauth") {
  96                 open UNIXAUTH, "|$config{unixauth_command}" or die("Could not run $config{unixauth_type}");
  97                 print UNIXAUTH "$user\n$password\n";
  98                 close UNIXAUTH;
  99                 $ret=!($?>>8);
 100         }
 101         else {
 102                 # no such authentication type
 103                 return 0;
 104         }
 105
 106         if ($ret) {
 107             my $userinfo=IkiWiki::userinfo_retrieve();
 108             if (! length $user || ! defined $userinfo ||
 109                 ! exists $userinfo->{$user} || ! ref $userinfo->{$user}) {
 110                     IkiWiki::userinfo_setall($user, {
 111                         'email' => '',
 112                         'regdate' => time,
 113                     });
 114             }
 115         }
 116
 117         return $ret;
 118     }
 119
 120     sub formbuilder_setup (@) {
 121         my %params=@_;
 122
 123         my $form=$params{form};
 124         my $session=$params{session};
 125         my $cgi=$params{cgi};
 126
 127         # if not under SSL, die before even showing a login form,
 128         # unless the admin explicitly says it's fine
 129         if (! exists $config{unixauth_requiressl}) {
 130                 $config{unixauth_requiressl} = 1;
 131         }
 132         if ($config{unixauth_requiressl}) {
 133             if ((! $config{sslcookie}) || (! exists $ENV{'HTTPS'})) {
 134                 die("SSL required to login. Contact your administrator.<br>");
 135             }
 136         }
 137
 138         if ($form->title eq "signin") {
 139                 $form->field(name => "name", required => 0);
 140                 $form->field(name => "password", type => "password", required => 0);
 141
 142                 if ($form->submitted) {
 143                         my $submittype=$form->submitted;
 144                         # Set required fields based on how form was submitted.
 145                         my %required=(
 146                                 "Login" => [qw(name password)],
 147                         );
 148                         foreach my $opt (@{$required{$submittype}}) {
 149                                 $form->field(name => $opt, required => 1);
 150                         }
 151
 152                         # Validate password against name for Login.
 153                         if ($submittype eq "Login") {
 154                                 $form->field(
 155                                         name => "password",
 156                                         validate => sub {
 157                                                 checkpassword($form->field("name"), shift);
 158                                         },
 159                                 );
 160                         }
 161
 162                         # XXX is this reachable? looks like no
 163                         elsif ($submittype eq "Login") {
 164                                 $form->field(
 165                                         name => "name",
 166                                         validate => sub {
 167                                                 my $name=shift;
 168                                                 length $name &&
 169                                                 IkiWiki::userinfo_get($name, "regdate");
 170                                         },
 171                                 );
 172                         }
 173                 }
 174                 else {
 175                         # First time settings.
 176                         $form->field(name => "name");
 177                         if ($session->param("name")) {
 178                                 $form->field(name => "name", value => $session->param("name"));
 179                         }
 180                 }
 181         }
 182         elsif ($form->title eq "preferences") {
 183                 $form->field(name => "name", disabled => 1,
 184                         value => $session->param("name"), force => 1,
 185                         fieldset => "login");
 186                 $form->field(name => "password", disabled => 1, type => "password",
 187                         fieldset => "login"),
 188         }
 189     }
 190
 191     sub formbuilder (@) {
 192         my %params=@_;
 193
 194         my $form=$params{form};
 195         my $session=$params{session};
 196         my $cgi=$params{cgi};
 197         my $buttons=$params{buttons};
 198
 199         if ($form->title eq "signin") {
 200                 if ($form->submitted && $form->validate) {
 201                         if ($form->submitted eq 'Login') {
 202                                 $session->param("name", $form->field("name"));
 203                                 IkiWiki::cgi_postsignin($cgi, $session);
 204                         }
 205                 }
 206         }
 207         elsif ($form->title eq "preferences") {
 208                 if ($form->submitted eq "Save Preferences" && $form->validate) {
 209                         my $user_name=$form->field('name');
 210                 }
 211         }
 212     }
 213
 214     sub sessioncgi ($$) {
 215         my $q=shift;
 216         my $session=shift;
 217     }
 218
 219     1
 220
 221 """]]